I. Field of the Invention
The present invention relates to radar detectors, and more particularly, to remote radar detectors in which the receiver unit is mounted outside the vehicle passenger compartment and the alert unit is mounted inside the vehicle passenger compartment to alert the driver to presence of police radar.
II. Description of Prior Art
Typical radar detectors are self-contained single units containing receiver circuitry and alert circuitry. The self-contained unit is typically mounted in the vehicle passenger compartment such as against the inside, middle of the windshield so as to detect police microwave and/or laser radar signals and to provide the driver with an audible and/or visual warning of the presence of such police radar signals. Remote radar detectors have been developed in which the receiver aspect of the detector is in a unit situated outside the vehicle passenger compartment, while the alert aspect of the detector is in a unit that continues to be mounted inside the vehicle passenger compartment. Such remote radar detectors allow for more optimal placement of the units so as to increase sensitivity of the receiver aspects of the detector and/or allow for more discreet positioning of the alert unit, such as along the dashboard or steering wheel column, instead of in the middle of the windshield. A cable or cord electrically connects the receiver unit from outside the vehicle passenger compartment to the alert unit mounted inside the vehicle passenger compartment. One example of a remote radar detector is shown in U.S. Pat. No. 4,952,937, in which the receiver portion is formed as part of a license plate frame.
While mounting of receiver units outside the vehicle passenger compartment has some advantages, it will be appreciated that the receiver unit is subject to significant environmental extremes and conditions. Thus, it has been found desirable to hennetically seal the receiver unit. Unfortunately, drastic fluctuations in temperature, for example, can cause significant changes in pressure inside the hermetically sealed unit which can cause poor performance or damage to the receiver unit. Additionally, even under the best of circumstances, there are times when the hermetic seal is simply insufficient to keep all moisture, for example, out of the receiver unit. Moreover, once the moisture invades the unit, it is difficult if not impossible for the moisture to escape from the unit thus leading in the long term to damage or failure of the receiver unit.